Nowadays, disposable test strips or sensors are generally used for detection of analytes in body fluids from lancets and puncturing aids.
U.S. Pat. No. 3,822,461 discloses a disposable lancet for puncturing human skin in order to obtain a volume of blood. The lancet according to this solution is designed in such a way that a minimum amount of material is used to produce it and, consequently, production costs are kept low. The design of the disposable lancets allows a plurality of lancets to be punched out from one material strip, so as to guarantee economic production. According to the method disclosed in U.S. Pat. No. 3,822,461, in which individual lancets are obtained with a puncturing portion at one end of a metal strip, and with a shoulder formed there, the respective individual lancet is punched out from a material strip. The width of the material strip corresponds substantially to the length of the lancet. The lancets are punched out alternatingly from the strip, the tip of one lancet pointing in one direction, and the individual lancet to be punched out next to this one facing in the other direction. In each punching operation, individual lancets are obtained whose outer contour is defined by the punching tool. Each of the lancets punched out comprises an elongate depression which reaches from the handling end to the puncturing end of the lancet and stiffens the latter in such a way as to increase the stiffness and the security against bending of each lancet punched out from the continuous strip, so that the lancet does not buckle during use.
Furthermore, DE197 53 847 A1 discloses an analytical test element with a capillary channel. This analytical test element is used to determine an analyte in a liquid and comprises an inert support, a detection element, and a channel suitable for capillary liquid transport. This channel has a sample application opening at one end, and a vent opening at the other end. The channel suitable for capillary liquid transport is at least partially formed by the support and the detection element. The channel for capillary liquid transport reaches from the sample application opening at least as far as that edge of the detection element lying nearest the vent opening. A recess is situated in a surface forming the channel suitable for capillary liquid transport, at that edge of the test element forming the sample application opening. In this way, that edge of the test element forming the sample application opening is at least partially interrupted on one side, the surface located opposite the recess lying free. At least one of the faces forming the inner surface of the channel suitable for capillary liquid transport is made hydrophilic. This is done either by using a hydrophilic material or by coating a less hydrophilic material with a hydrophilic layer. A layer of oxidized aluminium, for example, is suitable for rendering it hydrophilic.
According to the solution known from DE 197 53 847 A1, a two-sided adhesive tape is affixed. This includes a cutout which is a few millimeters in width and several millimeters in length and by means of which the dimension of the capillary channel is defined. A detection film, specifically designed for the detection of glucose for example, is affixed to the adhesive tape. The detection film covers the central, notch-like cutout in the adhesive tape. A cover layer is affixed to the exposed area of the adhesive tape so that the cover layer and detection film lie directly on one another. The cover layer is a laminate of a relatively thick, stable plastic film and a thin hydrophilic AluOx layer. The hydrophilic layer has to extend into the gap between the cover layer and detection film. When the cover layer is fitted on the adhesive tape, it is necessary to arrange the protruding end of the thinner film, i.e. of the thin hydrophilic AluOx layer, between the detection element and the thicker film of the cover layer. In such a production method, errors can arise because of the large number of adhesion operations that have to be performed with great precision. Because of the method steps that have to be followed, this method is relatively time-consuming.
DE 101 42 232 A1 discloses an analytical aid with a lancet and a test element. The analytical aid includes a lancet having a lancet needle and a lancet body. The lancet needle is displaceable relative to the lancet body, the lancet body being made of an elastic material in the area of the tip of the lancet needle. This material is embedded into the tip of the lancet needle. An analytical test element is connected fixedly to the lancet body. Also disclosed is a lancet-containing analytical aid having a lancet which has a lancet needle and a lancet body. The lancet body is designed as a hollow body in the area of the tip of the lancet needle. The hollow body surrounds the tip of the lancet needle, said lancet needle being displaceable relative to the lancet body, and the hollow body being made at least partially of an elastic material, and an analytical test element which is connected fixedly to the lancet body.
An illustrated embodiment of the present invention provides a method by which puncturing and measuring devices may expediently be connected and may be produced in a substantially automated production process.
In one method step, a recess, preferably of triangular configuration, is produced on the band-shaped support material. In this way, a puncturing point is produced with which the human skin can be punctured. The edges delimiting the recess are ground and sharpened, in particular in the area of their point, so that a point suitable for puncturing the human skin is formed on one long side of the band-shaped support material. The side of the band-shaped support material, for which a thin metal film of 0.1 to 0.3 mm thickness can be used, is surrounded by a plastic material in order to protect against injuries and damage and to ensure sterility of the final product. A soft plastic strip, for example made of silicone, and surrounding the points, is preferably used for this purpose. That side of the band-shaped support material remote from the puncturing points is likewise provided with a strip of plastic material, in order to make handling easier, this strip of plastic material surrounding that side of the band-shaped support material is remote from the puncturing points. This strip, made of any desired plastic material, serves for better handling of the finished combination of lancet and test strip. At this stage in the production process, the band-shaped support material with the embedded lancet points, which are surrounded by soft plastic, for example silicone, can now be sterilized by β or γ irradiation.
By means of the method proposed according to the invention, individual puncturing/measuring disposable bodies can be produced in assembly line production while avoiding a separate movable lancet part. According to the proposed method, the lancet does not represent a separate individual part movable relative to the main body, as is known for example from DE 101 42 232 A1, but is instead a fixed component part thereof Thus, by means of the method proposed according to the invention, an assembly line production can be carried out which renders obsolete the separate transfer stage of joining together two components such as lancet and main body according to DE 101 42 232 A1.
The detection material is now applied to the band-shaped support material in which the puncturing points are formed and which is surrounded by a strip of silicone material at the side having the puncturing points, while the opposite side is provided with a strip of plastic material. The area between the soft plastic material covering the puncturing points and the plastic strip of the band-shaped support material facilitating handling is covered over with an affixed cover film which borders the detection element. The band-shaped support material is now completely covered over. At the side on which the ground and sharpened puncturing points are formed, the band-shaped support material is surrounded by a silicone strip, to which a cover film is adjoined. The cover film lies on a detection element which has been applied in strip form on the band-shaped support material and which in turn lies on the plastic material facilitating handling of the band-shaped support material. By means of the method proposed according to the invention, it is advantageously possible to ensure that the band-shaped support material, from which individual puncturing/measuring disposable bodies are separated, can be sterilized by β or γ irradiation prior to application of a detection element. After sterilization of the band-shaped support material is completed is the detection element applied, so that the function and mode of action of the detection element is not adversely affected by the sterilization of the band-shaped support material by β or γ irradiation, because it is not exposed to this irradiation, thanks to the fact that it is applied later to the band-shaped support material. The detection element can either be applied directly in the area of the sharpened puncturing points or can also be applied to depressions which have been incorporated in the band-shaped support material and which form a channel for capillary liquid transport. Both variations of the arrangement of the detection element are possible.
Individual puncturing/measuring disposable bodies are now separated at a separating edge which can be selected according to a division based on the width of the individual puncturing/measuring disposable bodies to be produced. The separation of the individual puncturing/measuring disposable bodies preferably takes place along a separating line which extends from the base of the recess symmetrically to the tip of the recess, which extends in each case between two grooves or notches. This separating line is an imagined virtual separating line and not actually formed in the band-shaped support material. Each of the individual puncturing/measuring disposable bodies formed in this way comprises a silicone material portion surrounding the puncturing point, a cover film covering the groove or notch, and a portion of a detection material adjoining these. Moreover, each of the individual puncturing/measuring disposable bodies produced in this way has, on the handling area, a portion of the plastic material. When the silicone strip portion is removed, the puncturing point is exposed. That portion of the individual puncturing/measuring disposable body surrounded by the plastic material is used for holding in a puncturing aid.
In a particularly advantageous manner, the puncturing and measuring devices can be produced from a continuous support material into which, according to one method step, depressions with a small width of approximately 0.25 mm have first been incorporated. An important feature of the application of the notches to the band-shaped support material is that the thin metal film preferably used as band-shaped support material, and of only a few tenths of a millimeter thick, is not pierced through, and instead form notches which, depending on the notching tool, can have a rounded notch base or a triangular notch base, for example. Other geometries of the base of the depressions are also possible.
By means of the individual puncturing/measuring disposable bodies produced in this way with a notch width or groove width of 0.25 mm and a notch length of 15 mm, it is preferably possible to collect approximately 100 nl of blood. The volume of the blood that can be taken up by the notch or groove and can be conveyed by capillary action to the detection element depends on the contour of the notch or groove. The measurement is performed using a suitable optics system which registers the wetted part of the detection field and evaluates its colour change.
The band-shaped support material used is preferably a thin metal film which as raw material is wound up in a coil, for example, and, during the production of the individual lancets, is removed from a store of the material at a certain speed of advance. Depending on the punching tool, whose geometry can be semicircular or triangular or of any other suitable form, the individual grooves or notches are applied on one side of the band-shaped support material.
The individual puncturing/measuring disposable bodies produced according to the production method set out here are characterized by low production costs per item, and it is also possible to ensure a uniform quality of the individual puncturing/measuring disposable bodies produced in this way.